1. Technical Field
The present invention relates to a physical quantity sensor, a pressure sensor, an altimeter, an electronic apparatus, and a moving object.
2. Related Art
A pressure sensor including a diaphragm that undergoes bending deformation under pressure is widely used (see JP-A-2005-37309, for example). In a pressure sensor of this type, the diaphragm typically includes a cavity that forms part of a wall portion, and a sensor device disposed on the diaphragm detects the amount of bending of the diaphragm to detect the pressure acting on the diaphragm.
For example, the transducer described in JP-A-2005-37309 is so configured that a recess is formed on the rear side of a silicon substrate to form a diaphragm and a vacuum chamber (cavity) made of polysilicon is provided on the front side of the silicon substrate. The sidewall of the vacuum chamber is connected to a portion thinned by the recess in the silicon substrate. That is, the silicon-substrate-side end of the sidewall surface of the vacuum chamber is located closer to the center of the diaphragm than the circumferential edge of the bottom of the recess in the silicon substrate in a plan view.
On the other hand, forming a cavity made of a metal has been proposed. However, in the transducer described in JP-A-2005-37309, in which the sidewall of the vacuum chamber is connected to the portion thinned by the recess in the silicon substrate, forming a vacuum chamber made of a metal undesirably causes the pressure-sensitive characteristic of the transducer to change with temperature due to the difference in coefficient of linear expansion between the vacuum chamber and the silicon substrate.